These include molecules in growth factor pathways (e.g., the human epidermal growth factor receptor 2 (HER2)), regulators of the cell cycle and apoptosis (e.g., the tumor protein p53 (encoded by TP53 gene)), cell adhesion factors (such as E-cadherin), immune checkpoint control modulators programmed death 1 and programmed death-ligand 1 (PD-1/PD-L1), and other molecules relevant to DNA, RNA, exosome, or epigenetic modifications.37,38 HER2 is the first clinically used molecular biomarker for GC patients. This evidence concerns the gene ERBB2 and gastric cancer.